As I often do after watching a movie I like, I read some reviews of Irrational Man to see what others were saying. NPR liked it, the New Yorker, too. But the majority of the critics as measured by Rotten Tomatoes thought it was a failure. When you actually go into the reviews, though, you find this:
"In his 60s stand-up act, Allen joked that he once cheated on a metaphysics exam by looking within the soul of the student sitting next to him; 50 years later he's still at it."
"It’s impossible to watch 'Irrational Man' and not be aware of Allen’s autobiography, an echo that extends beyond Jill and Abe’s May-December relationship. Allen indicts the ethical exceptionalism of Abe the Great Intellectual, but there’s little or no daylight between his protagonist and Woody the Great Artist."
"Once Abe latches onto his scheme, borrowing pieces of 'Crimes and Misdemeanors,' 'Match Point' and other, better Allen films, he regains his lust for life."
I shouldn't be surprised that critics reviewed the movie this way because that's they way they always talk about his movies. You have to mention May/December (is Phoenix really a December?), Allen's personal life (even when it has nothing to do with the movie at all), and earlier movies the reviewer liked better. They complain about Allen being obsessed with the same topics, and yet their reviews cover the same topics, even when they aren't at all relevant. There are many valid criticisms of this movie, but it's very hard to find them in negative reviews. Instead, you'll see a lot of petty, generic snark.
This movie isn't Annie Hall, we get it.